Subject: RE: [Isis-wg] When the next Seq. Number Exceeds Max. Sequence Num ber!

From: "Chan, Chung Ming" <[email-masked]>
Date: Fri, 18 Jan 2002 06:13:13 -1000

Harish,

I was troubled with the word "Disabled." 

Like in P2P circuit, should the IS Ack the received LSP with PSNP or just do
nothing until the elapse of MaxAge + ZeroAgeLifetime seconds then send LSP
with SN=1? 

Should there be no action on the LSP be taken by the IS until MaxAge +
ZeroAgeLifetime seconds have passed?

Ming

============================================================================
====
Hi
 When the LSP sequence number reaches a max sequence value (say fffffff ) ,
the next sequence number that is allocated for a new LSP by an IS is 1 . But
since 1 < fffffff , the LSP with seq=1 will be discarded if transmitted
immediately.

So the IS waits  MaxAge (time for the Remaininglifetime/age field of the LSP
(seq=ffffff) to get to zero ) + ZeroAgeLifetime (for the zero age LSP to
timeout and be purged from all routers database) , before transmitting the
new LSP.

rgds
Harish

-----Original Message-----
From: [email-masked]
[mailto:[email-masked]]On Behalf Of Chan, Chung Ming
Sent: Thursday, January 17, 2002 6:15 PM
To: [email-masked]
Cc: Chan, Chung Ming
Subject: [Isis-wg] When the next Seq. Number Exceeds Max. Sequence
Number!

Hi,

When the next Seq. Number Exceeds Max. Sequence Number!

I'm reading to ISO/IEC10589, Section7.3.16.1 and not quite understand what
the text means when it talks about "... the IS Network entity shall be
disabled for a period of at least MaxAge + ZeroAgeLifetime, ..."

"...
If an Intermediate system needs to increment its sequence
number, but the sequence number is already equal to
SequenceModulus - 1, the event attemptToExceed-
MaximumSequenceNumber shall be generated and the IS
Network entity shall be disabled for a period of at least
MaxAge + ZeroAgeLifetime, in order to be sure that any ver-
sions of this LSP with the high sequence number have expired.
When it is re-enabled the IS shall start again with sequence
number 1.
..."

What is the IS supposed to do with the LSP in question?
What is the IS itself supposed to do?

Thanks,

Ming Chan
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